Peripheral ignition system



Dec. 26, 1961 N. K. TURNBULL ET AL 3,014,425

PERIPHERAL IGNITION SYSTEM Filed June 23, 1959 a u a u M FIGEI.

FIG.2.

INVENTORS NORMAN K. TURNBULL DAVID J. KATSANIS w m cc 4 WLEYS= 3,014,425A, V g I I PERIPHERAL IGNITION SYSTEM Norman K. Tumbull, Pitman, N.J.,and David J. Katsanis, Philadelphia, Pa., assignors to the United Statesof America as represented by the Secretary of the Army Filed June 23,1959, Ser. No. 822,398 I I 1 Claim. (Cl. 102-46) (Granted under Title35, U.S. Code (1952), see. 266) The invention described herein may bemanufactured and used by or for the Government for governmental purposeswithout the payment to us of any royalty thereon.

This invention relates to ammunition, and has for its principal objectthe provision of an improved ignition system and method of operationwhereby the propellant of the charge is more effectively utilized thanheretofore.

In a previously known system of ignition, a central core of relativelyfast burning powder is surrounded by a propellant which burns at a muchslower rate. This prior system has the advantage that the propellant isburned more evenly because. it ismore quickly ignited from one of itsends to the other. It leaves something to be desired, however, withrespect to the residue of unburned propellant grains which aredischarged from the weapon and wasted. 9

This loss of unburned propellant is largely due to the fact that thecentral part of the propellant is first ignitedfv and the resultingflame moves outwardly into. the unburned propellant. Asa result, anappreciable part of the propellant is discharged from the weapon in anunburned state.

In accordance with the present invention, a more efficient use of thepropellant is effected by positioning the fast burning powder near theouter periphery of the propellant. This has the advantage that the flameoriginated by the fast burning powder travels toward the central axis ofthe propellant and the otherwise unburned propellant grains are forcedoutwardly into the surrounding sheet of flame where they ar'emorecompletely burned. q

The invention will be better understood from the following descriptionwhen considered in connection with the accompanying drawings and itsscope is indicated by the appended claim.

Referring to the drawings:

FIG. 1 is a view, partly in section, of

an explosive 80% of a diameter of said casing and the axis of said.

charge made in accordance with the present invention, I

and

FIG. 2 shows the construction of the tube which encloses the fastburning powder and the means for igniting this powder.

The charge depicted by FIG. 1 includes a casing 10 a which encloses arelatively slow burning propellant 11.:

Embedded in-this propellant and spaced from the inner wall of the casing10 is a tube 12 which is in the form of a helix and may consist of lead,soft aluminum, a plastic, a fabric or the like. 'The tube 12. surroundsa smaller 3314,4215 Patented Dec. 26., 1961 tube 13, is spaced therefromby spacers 14 (see FIG. 2 and grommets 15 and 16, and is supported bythe end walls 17 and 18 of the case 10. At its ignition end the tube 13terminates in a primer 19 which may be fired by a voltage applied to itthrough leads 20 or in any other conventional manner.

Between the tubes 12 and 13 is a relatively fast burning black powder21. The tube 13 contains an igm'tion or transfer powder which may becomposed of PE'IN (pentaerythritol tetranitrate) and a slower burningexplosive, with a resulting burning rate of about 12,000 feet persecond. The helical tube 12 is positioned coaxially within the casing 10containing the propellant (i1 and is spaced from the case by a distanceof about onetenth the inside diameter of the case 10 so that thediameter of the helix is about of the diameter of case 10. When loaded,the propellant 11 is positioned to cover the tube 12 completely.

When the primer 19 is fired, the flame moves along the tube 13 at a rateof about 12,000 feet per second. As the flame moves, the black powder 21is ignited and the ignition tube 12 progressively disintegrates,igniting the propellant column 11 near its periphery. The remainingcolumn of propellant is enclosed within a constricting cylindrical sheetof flame in which it is completely consumed. As a result, propellantscattering is minimized for the reason that the propellant grains arerestricted by the wall of flame. As will be apparent to those skilled inthe art, the helical distribution of the black powder igniter 21contributes to a uniform ignition of the propellant, resulting incomplete propellant combustion with consequential high-order function ofthe propellant charge. This, in turn, contributes greatly to smoothoperation of automatic weapons, increased velocities and improvedreproducibilit-y of data.

We claim:

In a casing containing a solid propellant, an ignition tube containingblack powder, a second tube imbedded in 7 of, arranging said ignitiontube inside said casing in the form of a helix, said helix having adiameter of about helix being coincident with an axis of said casing.

References Cited in the'file of this patent UNITED STATES PATENTSYarbrough Jan. 3, 1939

